1. Field of the Invention
The present invention relates to an automatic transmission control device for an automobile, and more particularly to an automatic transmission control device for an automobile which controls its shifting action to a predetermined position in response to an engine temperature or when the automobile cannot maintain its set fixed speed in stable driving.
2. Description of the Prior Art
A device is well known that electrically shifts and controls transmission gears of an automatic transmission automobile according to various driving conditions, and the link with a fixed speed driving apparatus, for example, makes the most suitable driving according to driving conditions.
The fixed speed driving apparatus mentioned above, for example, consists of such composition that the pressing of a set switch enables the automatic adjustment of the throttle valve, and can perform long time driving on the highway or the like at a fixed speed. In driving up a sloping road, however, the driving speed slows down from the set fixed speed and uphill capability decreases in this case. There arises such a problem that the transmission control is not performed correctly and responsively.
On the other hand, when the engine temperature does not reach up high enough suitably and the transmission gear is shifted up to a high speed position, the drive feeling and the operational handling of the automobile are put in a bad condition. Further, it takes time to warm up the engine.
In the prior art device, therefore, included therein is a shift control apparatus that restrains from shifting up to the overdrive position, when the driving speed remarkably slows down from the set fixed speed in driving up a sloping road, in other words, when deviation is enlarged from the set fixed speed, or when the cooling water does not reach up to a predetermined temperature.
In the shift control apparatus in the prior art, however, there are drawbacks in that uphill capability and the warm-up capacity of the engine of the automobile cannot be adequately compensated The drive feeling and the operational handling of the automobile cannot be maintained in good conditions, since the enlarged deviation from the set fixed speed or the low temperature of the cooling water simply restrain the transmission from shifting up to the overdrive position. Furthermore, in the shift control apparatus in the prior art there are drawbacks in that the input terminal numbers in a shift control circuit increase as detecting signal numbers increase, and that the composition becomes complicated.